Horizontal cavity surface emitting laser assembly features for heat assisted magnetic recording

ABSTRACT

A laser is configured to emit light along a substrate-parallel plane along a first surface of the laser. An etched facet is on an emitting end of a lasing cavity and an etched mirror is on another end of the lasing cavity. An etched shaping mirror redirects light received from the etched facet in a direction normal to the substrate-parallel plane. A slider comprises an optical input coupler configured to couple the light from the laser into a waveguide of the slider. At least one protrusion is disposed on the laser and at least one recession is disposed on the slider, the at least one protrusion and the at least one recession configured to align the laser with the slider to allow the light to be coupled into the optical input coupler.

RELATED PATENT DOCUMENTS

This application claims the benefit of Provisional Patent ApplicationSer. Nos. 62/286,181 and 62/286,185 filed on Jan. 22, 2016, to whichpriority is claimed pursuant to 35 U.S.C. §119(e), and which areincorporated herein by reference in their entirety.

SUMMARY

Embodiments disclosed herein are directed to a laser configured to emitlight along a substrate-parallel plane along a first surface of thelaser. An etched facet is on an emitting end of a lasing cavity and anetched mirror is on another end of the lasing cavity. An etched shapingmirror redirects light received from the etched facet in a directionnormal to the substrate-parallel plane. A slider comprises an opticalinput coupler configured to couple the light from the laser into awaveguide of the slider. At least one protrusion is disposed on thelaser and at least one recession is disposed on the slider, the at leastone protrusion and the at least one recession configured to align thelaser with the slider to allow the light to be coupled into the opticalinput coupler.

Embodiments described herein are directed to a laser configured to emitlight along a substrate-parallel plane along a first surface of thelaser. An etched facet is disposed on an emitting end of a lasing cavityand an etched mirror on another end of the lasing cavity. An etchedshaping mirror redirects light received from the etched facet in adirection normal to the substrate-parallel plane. A slider comprises anoptical input coupler configured to couple the light from the laser intoa waveguide of the slider. A series of protrusions are disposed on oneof the laser and the slider and a series of recessions are disposed onthe other of the laser and the slider. The series of protrusions and theseries of recessions are configured to align the laser with the sliderto allow the light to be coupled into the optical input coupler.

These and other features and aspects of various embodiments may beunderstood in view of the following detailed discussion and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The discussion below makes reference to the following figures, whereinthe same reference number may be used to identify the similar/samecomponent in multiple figures.

FIG. 1 illustrates a concept image of a HCSEL that is mounted on aread/write head or slider in accordance with various embodimentsdescribed herein;

FIGS. 2A and 2B show a different view of the slider and the HCSEL inaccordance with various embodiments described herein;

FIGS. 3A and 3B are a close-up view of bond pads on the HCSEL inaccordance with embodiments described herein;

FIGS. 4A and 4B show illustrates other views of the HCSEL having a bondpad array having N laser electrodes alternated with P laser electrodesin accordance with various embodiments described herein;

FIGS. 5A-5F illustrate a process for creating reference features in anHCSEL system in accordance with various embodiments described herein;

FIGS. 6A-6F show a process utilizing a mask to create a downtrackreference feature in accordance with various embodiments describedherein;

FIGS. 7A-7E show another process for creating reference patterns toalign the HCSEL with the slider in accordance with various embodimentsdescribed herein;

FIG. 8 illustrates another way of providing a mechanical alignment stopfor the system in accordance with various embodiments described herein;

FIGS. 9A-9D shows various configurations that provide crosstrack,downtrack, and/or vertical alignment in accordance with variousembodiments described herein;

FIGS. 10A and 10B illustrate an alignment system for a HCSEL and aslider using features positioned on one or both of the HCSEL and theslider that help guide the HCSEL into a desired position in accordancewith various embodiments described herein;

FIG. 11A shows reference posts 1140 that can be fabricated outside ofthe HCSEL and/or mirror region in a position that coincides with wherevarious reference features are located in accordance with variousembodiments described herein;

FIGS. 11B-11D illustrate the process for creating reference posts 1140on the HCSEL surface in accordance with various embodiments describedherein;

FIG. 11E illustrates a process for creating reference posts on the HCSELsurface in accordance with various embodiments described herein;

FIGS. 12A and 12B show an example in which fiducial marks are used toalign the HCSEL to the optical input coupler in accordance with variousembodiments described herein;

FIGS. 13A and 13B illustrates a solder pad configuration using an arrayof solder pads on the N and P electrodes in accordance with variousembodiments described herein;

FIGS. 14A-14F illustrate laser systems having folded cavities andassociated solder embodiments to enable thermal conduction andself-alignment in accordance with various embodiments described herein;and

FIGS. 15A-15D illustrate using bonding material to create complete orpartial sealing rings and/or mechanical filters that prevent mechanicalparticles and/or liquids from coming into the laser emission, lasershaping mirror, and/or coupler space cavities in accordance with variousembodiments described herein.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying setof drawings that form a part of the description hereof and in which areshown by way of illustration of several specific embodiments. It is tobe understood that other embodiments are contemplated and may be madewithout departing from the scope of the present invention. The followingdetailed description, therefore, is not to be taken in a limiting sense.

The present disclosure is generally related to heat-assisted magneticrecording (HAMR), also referred to as energy-assisted magnetic recording(EAMR), thermally-assisted recording (TAR), thermally-assisted magneticrecording (TAMR), etc. In a HAMR read/write head, a near-fieldtransducer concentrates optical energy into a tiny optical spot in arecording layer, which raises the media temperature locally. The hotspotreduces the writing magnetic field required for high-density recording.This disclosure describes aspects of integrating a Horizontal CavitySurface Emitting Laser (HCSEL) into a HAMR read/write head beingdeveloped for hard disc drives (HDDs). It is to be understood that“laser” may be used interchangeably with “HCSEL” in this disclosure.

FIG. 1 illustrates a concept image of a HCSEL that is mounted on aread/write head or slider. For this disclosure, the terms “read/writehead”, “head”, and “slider” will be used interchangeably and are torepresent a read/write head for hard disk drives. The HCSEL laser diode110 is mounted upon the back slide of the slider 120. The HCSEL 110emits light 106 that is reflected into an optical input coupler 150 byan etched shaping mirror 130. The light profile 155 is shown as itenters the slider 120 from the HCSEL 110. The optical input coupler 150couples light from the HCSEL 110 into the waveguide 160. The waveguideis designed to concentrate the light into an optical spot on the mediaas shown by light profile 165.

FIGS. 2A and 2B show a different view of a slider 220 and HCSEL 210. Aplurality of bond pads 215 may be disposed on the HCSEL 210 and/or theslider 220. A bonding material such as solder, for example, may bedisposed on the bonding pads. The bond pads 215 may be used for variouspurposes. For example, the bond pads 215 may be used for mechanicalattachment, electrical connection, thermal connection, and/or alignmentof the HCSEL 210 with the slider 220. In some cases, a reflow of thebonding material induces relative movement between the HCSEL 210 and theslider 220. This relative movement may facilitate alignment of featuresof the HCSEL 210 with features of the slider 220.

FIGS. 3A and 3B are a close-up view of bond pads on the HCSEL inaccordance with embodiments described herein. A bond pad array isdisposed on a single side of the HCSEL that faces the slider. The bondpad array includes N laser electrode material (cathode) 310 alternatedwith P laser electrode material (anode) 320 on the single side of theHCSEL. Laser light emerges from laser cavity under the P-electrode intomirror 330 which serve to both shape the emerging light and re-directthe direction (for example, perpendicular to the laser cavity).

FIG. 4A illustrates another view of the HCSEL with a bond pad arrayhaving N laser electrodes 420 alternated with P laser electrodes 410 anaccordance with various embodiments. Light is output at facet 430 wherethe shaping mirror helps to couple the laser light into the opticalinput coupler of the slider. FIG. 4B illustrates a side view of theHCSEL 440 having bond pads 415 on a side of the HCSEL 440 that faces theslider.

With a standard edge-emitting laser diode, light is emitting out of thelaser cavity parallel to the cavity layer and with diverging beamcharacteristics. With an HCSEL, the orientation of the light source isredirected (compared to an edge-emitting laser) using a reflectingmirror and as a result, the location of the surfaces that are preciselydefined or referenced on the laser and the slider are also changed. Inaddition, in some HCSEL fabrication methods, the mirror can be shaped inmanner that not only redirects the light but also shapes beam usingprinciples of reflective optics. In some cases, defining a method toalign the output position of the laser to the optical input coupler insuch a way that manufacturing tolerances or realistic assembly tools canachieve the acceptable alignment tolerance. (e.g., microns or submicron)may be desirable. One method to facilitate alignment of the HCSEL withthe slider may utilize reference features located on one or both of theHCSEL and the slider. The reference features may be used to define areference surface and/or as a physical stopper to aide in the alignmentof the HCSEL with the slider.

The fabrication of stoppers may pose some challenges as a desiredtolerance may be very small and therefore the thickness variation of theprocess may also need to be small for precise alignment. FIGS. 5A-5Fillustrate a process for creating reference features in an HCSEL system.A basecoat, cladding, and other read/write layers 520 are fabricated ona substrate 510. According to one implementation, the substratecomprises AlTiC. Optical coupler and/or core layers 530 are depositedand/or patterned on the other layers 520. The layers may be fabricatedusing thin-film deposition, photolithography, etching, and/or using alift-off process, for example. Using these techniques allows fordeposition thickness control of the layers. The control of thedeposition thickness facilitates a precise position reference withrespect to other components. Precise thickness may be desirable foralignment and/or positioning of the components. A top cladding layer 525is deposited on the core layers 530 as shown in FIG. 5B. A sacrificiallayer 540 is deposited on the top cladding layer 525 as shown in FIG.5C. In some cases, the sacrificial layer material is chosen such that itcan be selectively wet etched with respect to the other materialssurrounding it. For example, the sacrificial layer 540 may comprisecopper. The sacrificial layer 540 may be patterned such that it is onlyin a desired precise region that will end up exposed on the top side ofthe slider. The patterning process may be done by an etching, a plating,and/or a lift-off process, for example. In some cases, certain relatedprocessing or release-etch steps can utilize a non-precise mask (i.e. aphotolithography masks that may have significantly less alignmentrequirements than the defining sacrificial feature) For example, in someembodiments, a protective mask could be patterned on other regions ofthe slider during the selective sacrificial etch but be recessed byseveral microns from the edge of the sacrificial feature to be removed.This may allow exposure of the sacrificial material by the etchantswhile generally protecting the areas not to be etched if the materialsurrounding the sacrificial material is highly selective to thesacrificial etchant. An example of this is shown in FIG. 7C as describedbelow.

The sacrificial layer 540 is encapsulated and/or planarized as shown inFIG. 5D with a cladding material 527. The cladding material 527 used toencapsulate the sacrificial layer 540 may be the same or differentcladding material as that of the top cladding layer 525. In some cases,the cladding material used to encapsulate the sacrificial layer 540comprises Al₂O₅. The sacrificial layer 540 is patterned such that it isin a desired location that will end up exposed on the top side of theslider. The sacrificial layer 540 may be exposed on the top of theslider near the optical input coupler by implementing a bar slice alongthe dotted line 550 shown in FIG. 5E. FIG. 5F shows a plurality ofexposed sacrificial layers 540. At some point in the process, thesacrificial layer 540 is removed by using a wet etch process, forexample. The surface that is left behind after the removal of thesacrificial layer 540 allows for very precise position control withrespect to the optical input coupler and the HCSEL.

According to various implementations, a mask layer is used to create adown-track reference feature. FIGS. 6A-6F show a process utilizing amask to create a downtrack reference feature in accordance with variousembodiments described herein. Similar to FIGS. 5A-5F, a basecoat,cladding, and other read/write layers 620 are fabricated on a substrate610. Optical input coupler and/or core layers 630 are deposited and/orpatterned on the other layers 620. A top cladding 625 is deposited onthe core layers 630. A sacrificial layer 640 is deposited on the topcladding layer 625. It may be desirable to etch away a portion of theslider body 612 to enable interaction between the reference feature 670in the slider with the reference feature 689 on the laser; this avoidsthe need for laser reference feature 689 to be protruding a longdistance. In this embodiment, a mask layer 660 is deposited on thesacrificial layer 640 and at least a portion of the top cladding layer625, the core layer 630, and the cladding layers 620 as shown in FIG.6B. An etching process is performed and portions of the substrate 612and the basecoat, cladding and/or other read/write layers 622 that arenot covered by the mask layer 660 are etched and/or otherwise removed asshown in FIG. 6C. According to various implementations, the etch istimed such that only a desired portion of the system that is not coveredby the mask layer is etched. The mask layer 660 and the sacrificiallayer 640 are then removed leaving behind a reference feature 670.

FIG. 6E shows a HCSEL system with a reference feature 670 defined withrespect to the laser emission and/or focus point from the mirror 695.This can be further combined with solder self-alignment pads 682, 687disposed on the HCSEL 680 and/or the slider 685. The solderself-alignment pads 682, 687 may help with alignment by using a reflowprocess and surface tension forces to self-align the laser into adesired cross-track and downtrack alignment. The HCSEL 680 and/or theslider 685 moves along the arrows 690 during the reflow process toobtain precise alignment. In some cases, the alignment pads on the HCSEL682 are offset from the pads on the slider 687. The amount that the padsare offset may be chosen to cause surface forces to push the referencesurfaces into contact before the features are self-centered. Having thepads offset may allow for more flexibility in the manufacturingtolerance of the device as the precise alignment can be achieved througha solder reflow process as described above. In some cases, thedown-track alignment can be precisely defined by the HCSEL referencesurface 689 physically hitting against the reference surface 670 thatwas created by removal of the sacrificial material. FIG. 6F shows thereference feature 689 of the HCSEL 680 physically preventing the slider685 and/or the HCSEL 680 from shifting past the reference feature 689.

FIGS. 7A-7E show another process for creating reference patterns toalign the HCSEL with the slider. The fundamental approach for creating areference surface 770 with precise control to the input coupler is thesame, but this embodiment positions the interaction with laser referencefeature on the other side of the waveguide. In this process, a basecoat,cladding, and other read/write layers 720 are fabricated on a substrate710. Optical input coupler and/or core layers 730 are deposited and/orpatterned on the other layers 720. A top cladding 725 is deposited onthe core layers 730. A sacrificial layer 740 is deposited between thesubstrate 710 and the optical input coupler and/or core layers 720 asshown in FIG. 7A. A first mask layer 762 is deposited on at least aportion of the substrate and a second mask layer 760 is deposited on atleast a portion of the sacrificial layer 740 and at least a portion ofthe top cladding layer 725, the core layer 730, and the basecoat,cladding layers and/or other write layers 720 as shown in FIG. 7B. Anetching process is performed and portions of the substrate 712 areremoved that are not covered by the first mask layer 662 and/or thesecond mask layer 660 as shown in FIG. 7C. The sacrificial layer 740 isthen removed to create a system having the reference feature 770 asshown in FIG. 7D.

FIG. 7E shows a HCSEL system with a reference feature 770 defined withrespect to the laser emission and/or focus point from the mirror 795.This can be further combined with solder self-alignment pads 782, 787disposed on the HCSEL 780 and/or the slider 785. Similarly to theearlier discussion, the solder self-alignment pads 782, 787 may helpwith alignment by using a reflow process that uses surface tensionforces to self-align the laser 780 into a desired cross-track anddowntrack alignment. The HCSEL 780 and/or the slider 785 moves along thearrows 790 during the reflow process to obtain precise alignment. TheHCSEL 780 also has a reference feature 789 that, combined with thereference feature 770 on the slider 785 mechanically prevents the slider785 and/or the HCSEL 780 from shifting beyond the reference feature 770.

FIG. 8 illustrates another way of providing a mechanical stop for thesystem. The key difference in this embodiment is the use of an additivereference feature 870 that relies on precise photolithographypositioning during a slider back-side process. The HCSEL 880 has areference feature 889 formed on the surface facing the slider 885. Amechanical reference feature 870 is directly patterned on the slider 885surface facing the HCSEL 880. In some cases, the mechanical referencefeature 870 is patterned on the slider using a precision lithographyprocess. As in previous figures, the combination of the referencefeature 889 of the HCSEL 880 and the reference features 870 of theslider 885 mechanically allows for precise alignment of the system. Thesolder self-alignment pads 882, 887 may help with alignment by using areflow process that uses surface tension forces to self-align the laserinto a desired cross-track and downtrack alignment as at least one ofthe HCSEL 880 and the slider moves along arrows 890. The alignmentsystem described in FIG. 8 shows alignment of the laser emission and/orfocus point from the mirror 895 with the optical input coupler of theslider 885.

While FIGS. 5A-8 show various ways to provide precise alignment of thesystem, other additional or alternative ways exist to provide precisealignment. FIGS. 9A-9D shows various configurations that providecrosstrack, downtrack, and/or vertical alignment that can be used inaddition to or as an alternative to the systems shown in FIGS. 5A-8. Insome cases, no reference features are used and the system relies solelyon the solder self-alignment process described above. FIG. 9Aillustrates an example in which the solder self-alignment pads 990disposed on the slider 985 and/or the HCSEL 980 and are used to provideprecise alignment of the slider 985 with the HCSEL 980. FIG. 9B shows anexample in which one or more vertical stoppers 995 in-between solderself-alignment pads 991 disposed on the slider 986 and/or the HCSEL 981are used to provide precise alignment of the slider 986 with the HCSEL981.

In some cases, reference features on one or both of the HCSEL and theslider are used in combination or instead of the vertical stoppers. FIG.9C shows an example in which a reference feature 915 of the HCSEL and areference feature 925 of the slider is used in combination with verticalstoppers 996 in-between solder self-alignment pads 992 disposed on theslider 987 and/or the HCSEL 982 are used to provide precise alignment ofthe slider 987 with the HCSEL 982. FIG. 9D illustrates an example inwhich a reference feature 917 of the HCSEL is used in combination withvertical stoppers 997 in-between solder self-alignment pads 993 disposedon the slider 988 and/or the HCSEL 983 are used to provide precisealignment of the slider 988 with the HCSEL 983. In the example shown inFIG. 9D, the reference feature 917 of the HCSEL is disposed between asolder self-alignment pad 993 and a vertical stopper 997. Thecombination of the vertical stopper 997 and the reference feature 917may provide for a mechanical stop to aide in alignment of the system.The vertical stoppers described in 9B-9D may provide precise verticalalignment for the system. In a system lacking vertical stoppers, theheight of the system may be controlled by control of the solder volume.In some cases, a HCSEL system may have a laser that has a tolerance toaccount for a system lacking in vertical stoppers.

According to various embodiments, different methods may be used fordowntrack, crosstrack and/or vertical alignment. FIGS. 10A and 10Billustrate an alignment system for a HCSEL and a slider using featurespositioned on one or both of the HCSEL and the slider that help guidethe HCSEL into a desired position. FIG. 10A illustrates a HCSEL 1010having multiple ball-type features 1030. While FIG. 10A illustrates thealignment features and/or protrusions on the HCSEL having rounded edges,it is to be understood that the alignment features 1030 may have anyshape. These features are designed to aid in self alignment by fittinginto corresponding recessions 1040 in the surface of the slider 1020facing the HCSEL 1010. The shape of the features 1030 and/or therecessions 1040 may be designed to guide the HCSEL 1010 into a desiredposition with respect to the slider 1020. While FIG. 10A shows therecessions 1040 disposed on the slider 1020 as having a different shapethan the features on the HCSEL 1010, it is to be understood that thefeatures and the recessions may have similar, but opposite shapes suchthat the features fit substantially perfectly into the recessions. Insome, cases, the difference in the shape of the features and therecessions allows for more accurate alignment than if the shapes werecomplementary shapes. Bond pads 1050, 1060 are disposed on one or bothof the HCSEL 1010 and the slider 1020.

FIG. 10B illustrates an example system in which the alignment features1055 are on the slider and the corresponding recessions 1035 are locatedon the HCSEL. In some cases, the features and recession shown in FIGS.10A and 10B can be used in combination or alone as a coarse adjustmentand then a solder reflow process may be used to provide a fineralignment. The features and recessions described in FIGS. 10A and 10Bmay be used in addition to or as an alternative to any of the otheralignment methods described in this disclosure. While FIGS. 10A and 10Billustrate a system having triangular recessions, it is to be understoodthat the recessions can have any shape including three dimensionalshapes. For example, the recessions can comprise have square shapes,slots, v-grooves, and/or tetrahedral shapes. In some cases, there ismore than one shape for the protrusions and/or the recessions in asingle system.

To obtain the rounded “ball”-type shapes 1055 in the slider or 1030 inthe laser, one can use methods involving photoresist reflow to create arounded profile (as the etch mask is uniformly removed, the roundedshape of the photomask is etched into the substrate underneath). Thetriangular grooves in the slider 1040 or laser 1035 can be formed byvarious wet or dry etching methods.

The number of alignment features can be defined by three holes tokinematically define the plane and rotation of the laser. Additionalalignment holes (e.g. four instead of three) are theoretically redundantto define the alignment plane and rotation, but may be utilized to allowfor fabrication tolerances.

According to various embodiments described herein, protruding featuressuch as posts can be etched or deposited as the HCSEL laser and/or theslider is processed at the wafer level. Features created on the HCSELand/or the slider during processing using a wafer-level lithographymethod can achieve sub-micron alignment between the features on theHCSEL. The features on the HCSEL may include one or more of bond pads,self-alignment pads, an output facet, and/or an etched shaping mirror.FIG. 11A shows reference posts 1140 that can be fabricated outside ofthe HCSEL and/or mirror region in a position that coincides with wherevarious reference features are located.

FIGS. 11B-11D illustrate the process for creating reference posts 1140on the HCSEL surface. Device layers 1150 are fabricated on a substrate1160. The device layers may include cladding, optical coupler, corelayers and/or other read/write layers. According to variousimplementations, the substrate 1160 comprises AlTiC. In this example,the reference features are etched at the same time as the other featuresof the laser. For example, the alignment post 1156 is created at thesame time as the rear facet 1152, the front facet 1154, and the shapedmirror 1180. According to various embodiments, features of the HCSELexcept for the alignment post are etched to leave the protrudingalignment post 1155. This selective etching process may be done by usingvarious sacrificial layers and/or masks as described in conjunction withearlier figures. In some cases, the alignment post is deposited after orduring the formation of other laser features as shown in FIG. 11E. Inthis case, the alignment post 1170 is deposited on top of the otherlaser features after or during fabrication of the other laser features.

In accordance with various embodiments fiducial marks on the HCSELand/or the slider are used to align various components. FIGS. 12A and12B show an example in which fiducial marks are used to align the HCSELto the optical input coupler. The fiducial marks can be patterned on theHCSEL and/or the slider at any time during the fabrication process.After fabrication and processing of the slider, the fiducial marks 1220are exposed on the top side of the slider 1210 that faces the HCSEL asshown in FIG. 12A. Matching openings 1240 are exposed on the HCSEL 1230on the side of the HCSEL 1240 facing the slider 1210. While FIGS. 12Aand 12B show that the fiducial marks and the corresponding openings arecrosses, it is to be understood that the fiducial marks can have anyshape. An infrared camera can be used to align the fiducial marks withthe corresponding openings on the HCSEL. During the alignment process,the fiducial mark appears transparent on the infrared camera and thesurrounding area appears opaque. This allows direct alignment of theHCSEL with the slider through infrared imaging of the laser.

As described above, self-alignment pads have been may be used to providealignment between the various features of the slider and the laser. Thesurface tension in reflowing solder that is in contact with two bondpads is used to guide alignment. In some cases, a greater number ofalignment pads increases the surface area and thus results in betteralignment precision. Various factors may be considered when designing analignment system. For example, one or more of the following factors maybe considered (1) providing enough surface area for preciseself-alignment, (2) providing large enough pads to allow a coarsealignment of the laser (prior to self-alignment reflow), (3) providinggood thermal cooling from the heat-generating laser cavity to theslider, and/or (4) providing electrical connection to the P and Nelectrodes on the laser and possibly to additional elements on the lasersuch as an integrated photodiode and/or a heater.

FIG. 13A illustrates a solder pad configuration using an array of solderpads on the N and P electrodes. In this example, the solder pads fullycover the surface of the P and N electrodes. The laser cavity 1320follows along in a substantially straight line along a column of thesolder pads. FIG. 13B shows another configuration in which there is acontinuous bond pad 1330 disposed beneath the laser cavity 1325. Thecontinuous bond pad may provide more continuous cooling and or betterelectrical connection to the laser cavity 1325.

While the configurations shown in FIGS. 13A and 13B illustrated asubstantially straight laser cavity, in some cases, the laser cavity mayhave a folded configuration. This can be done by using etched facets tocreate the laser cavity and align and/or integrate the laser cavity withand etched shaping mirror and/or alignment features. A folded cavity maybe created by providing multiple reflecting surfaces that are etched tocreate the folded cavity. The increase in cavity length that the foldedcavity provides may enable higher power with less reliability risk ofself-heating. The folded cavity may also allow for a more compact designso that the HCSEL fits into the constraints of the application, e.g., aHAMR system. In a folded laser cavity, the laser cavity has at least onebend and may include a series of bends. The laser cavity is uniformlycooled below the laser cavity shape.

FIGS. 14A-14E illustrate laser systems having folded cavities. In FIGS.14A and 14B, the laser cavity length is the same size as the cavitylength illustrated in FIGS. 13A, and 13B, but the laser is shorter sothe cavity is folded to accommodate the laser length. While the exampleshown in FIG. 14A shows a laser cavity having two bends, it is to beunderstood that the folded laser cavity can have more or fewer bends.Similarly as in FIGS. 13A and 13B, solder pads are located onsubstantially the entire surface of the P and N electrodes. FIG. 14Bshows the folded laser cavity of FIG. 14A without the solder pads for abetter view of the cavity. FIGS. 14C and 14D show another example of afolded laser cavity with a similarly sized laser as in FIGS. 13A in 13B.In this case, the laser cavity 1430 has a series of bends. FIGS. 14E and14F illustrate another example of a folded laser cavity 1440 where theemission output is offset with respect to the electrode. In some cases,the folded lasing cavity comprises at least one curve.

While FIGS. 13A-14F illustrate circular solder pads, it is to beunderstood that the solder pads can be any shape. For example, thesolder pads can have a square or a triangular shape, for example. Insome cases, the solder pads are not a uniform size and/or shape suchthat the size and/or shape varies between different solder pads. Forexample, the solder pads on the P electrode may be a different sizeand/or shape than solder pads on the N electrodes. In some embodiments,the solder pads do not cover the entire surface of the P and/or Nelectrodes. For example, the solder pads may cover only a portion of theP and/or N electrodes. In some cases, the solder pads may only bepresent underneath the laser stripe.

According to various implementations, contamination in the optical pathor on the laser surface can lead to laser failures on the output facetor blockage of the optical path between the laser emission and opticalcoupler input. FIGS. 15A-15D illustrate using bonding material to createcomplete or partial sealing rings and/or mechanical filters that preventmechanical particles and/or liquids from coming into the laser emission,laser shaping mirror, and/or coupler space.

FIG. 15A shows a completely closed sealing barrier 1510 around the laseremission and mirror area 1505. The sealing barrier may be formed using abonding material. For example, the bonding material used may be the samebonding material that is disposed between the pads as described above.The bonding material may completely surround the laser emission andmirror area 1505 and a sealing material may be used to provide anairtight seal. In some cases, the bonding material and/or the sealingmaterial comprises solder. In some cases, a sealing material is not usedallowing some airflow and preventing pressure build-up. According tovarious implementations, the height of the N and P contacts is offsetsuch that the P contact is higher than one or both of the P contacts. Insome cases, the N and P contacts are at substantially the same height.In some cases, a ridge 1525 is formed between the N and P contactsfacilitating a same or similar height of the N and P contacts as shownin FIG. 15B. FIG. 15C illustrates an example in which the sealing ring1530 is not sealed and an opening 1535 is provided. The opening 1535 maybe configured to prevent pressure build up from the thermal heat upduring the laser operation. FIG. 15D shows another configuration inwhich a series of mechanical barriers are used to act as a mechanicalfilter preventing particles from reaching the laser area. In all of thecases of FIGS. 15A-15D the mechanical barriers may or may not be bondedto the slider. These may or may not be directly bonded to the head.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein. The use of numerical ranges by endpointsincludes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, and 5) and any range within that range.

The foregoing description of the example embodiments has been presentedfor the purposes of illustration and description. It is not intended tobe exhaustive or to limit the embodiments to the precise form disclosed.Many modifications and variations are possible in light of the aboveteaching. Any or all features of the disclosed embodiments can beapplied individually or in any combination are not meant to be limiting,but purely illustrative. It is intended that the scope of the inventionbe limited not with this detailed description, but rather determined bythe claims appended hereto.

What is claimed is:
 1. An apparatus, comprising: a laser configured toemit light along a substrate-parallel plane along a first surface of thelaser; an etched facet on an emitting end of a lasing cavity and anetched mirror on another end of the lasing cavity; an etched shapingmirror that redirects light received from the etched facet in adirection normal to the substrate-parallel plane; a slider comprising anoptical input coupler configured to couple the light from the laser intoa waveguide of the slider; and at least one protrusion on the laser andat least one recession on the slider, the at least one protrusion andthe at least one recession configured to align the laser with the sliderto allow the light to be coupled into the optical input coupler.
 2. Theapparatus of claim 1, wherein the at least one protrusion is formedduring fabrication of the laser.
 3. The apparatus of claim 1, whereinthe at least one protrusion is deposited after the fabrication of thelaser.
 4. The apparatus of claim 1, wherein the slider further comprisesa mechanical reference feature configured to align the laser with theslider.
 5. The apparatus of claim 4, wherein the mechanical referencefeature is fabricated using a wafer-level sacrificial layer.
 6. Theapparatus of claim 5, wherein the mechanical reference feature isdisposed on at least a portion of a waveguide core layer.
 7. Theapparatus of claim 5, wherein the mechanical reference feature isdisposed adjacent a substrate layer of the slider.
 8. The apparatus ofclaim 1, further comprising fiducial marks on the slider andcorresponding openings on the laser, wherein the fiducial marks are usedto align the laser to the slider.
 9. The apparatus of claim 1, whereinthe at least one protrusion is ball shaped.
 10. The apparatus of claim1, wherein the at least one protrusion and the at least one recessionare configured to provide one or more of crosstrack, downtrack, andvertical alignment.
 11. The apparatus of claim 1, further comprising aplurality of alignment pads on the surface of at least one of the sliderand the laser, the alignment pads configured to align the laser with theslider and associated slider optical elements.
 12. The apparatus ofclaim 11, further comprising a vertical stopper between at least onepair of the plurality of alignment pads, the vertical stopper configuredto provide vertical alignment of the slider with the laser.
 13. Anapparatus, comprising: a laser configured to emit light along asubstrate-parallel plane along a first surface of the laser; an etchedfacet on an emitting end of a lasing cavity and an etched mirror onanother end of the lasing cavity; an etched shaping mirror thatredirects light received from the etched facet in a direction normal tothe substrate-parallel plane; a slider comprising an optical inputcoupler configured to couple the light from the laser into a waveguideof the slider; and a series of protrusions on one of the laser and theslider and a series of recessions on the other of the laser and theslider, the series of protrusions and the series of recessionsconfigured to align the laser with the slider to allow the light to becoupled into the optical input coupler.
 14. The apparatus of claim 13,wherein the series of protrusions and the series of recessions areconfigured to provide one or more of crosstrack, downtrack, and verticalalignment.
 15. The apparatus of claim 13, further comprising a pluralityof alignment pads on the surface of at least one of the slider and thelaser, the alignment pads configured to align the laser with the sliderand associated slider optical elements.
 16. The apparatus of claim 15,further comprising a vertical stopper between at least one pair of theplurality of alignment pads, the vertical stopper configured to providevertical alignment of the slider with the laser.
 17. The apparatus ofclaim 13, wherein a bonding material is disposed between alignment padsof the slider and alignment pads of the laser and a reflow of thebonding material allows relative movement between the slider and thelaser to align the slider with the laser.
 18. The apparatus of claim 13,wherein the protrusions have curved edges and the recessions havestraight edges.
 19. The apparatus of claim 13, wherein the protrusionsare ball shaped.
 20. The apparatus of claim 13, wherein a shape of therecessions comprises one or more of square, triangular and tetrahedralshapes.